Circuit breaker

Abstract

An electronically controlled latching circuit breaker capable of being remotely set or tripped. The electronic controls are current sensitive rather than thermally activated.

We claim: 
     
       1. A circuit breaker comprising, current sensing means for producing a sensor signal representative of a current value in a current path,   reference signal producing means for producing at least one reference signal,   comparator means for comparing said reference signal with said sensor signal,   said comparator means operative to produce an error signal when said sensor signal differs from said reference signal,   frequency generator means for producing a frequency signal,   counter means connected to said frequency generator means and to said comparator means,   said counter means operative to receive and count said frequency signal when said comparator produces said error signal,   said counter means operative to produce a counter signal when said counter means has counted a prescribed number of said frequency signals,   latch circuit means connected to said counter means to receive said counter signal and produce a first latch signal in response thereto,   logic circuit means connected between said counter means and said latch circuit means, and   switch means connected to said latch circuit means to receive said first latch signal whereby said switch means is operated to interrupt said current path.   
     
     
       2. The circuit breaker recited in claim 1 wherein, said switch means includes, contact means connected in the current path to selectively pass current therethrough, and   armature means connected to said contact means to selectively open said contact means.     
     
     
       3. The circuit breaker recited in claim 1 wherein, said current sensing means comprises a current transformer.   
     
     
       4. The circuit breaker recited in claim 1 wherein, said current sensing means comprises a Hall-effect device.   
     
     
       5. The circuit breaker recited in claim 1 wherein, said current sensing means comprises a transformer/saturable reactor combination.   
     
     
       6. The circuit breaker recited in claim 1 wherein, said reference signal means comprises a voltage divider network.   
     
     
       7. The circuit breaker recited in claim 1 wherein, said comparator means includes a plurality of comparator circuits each of which compares said sensor signal with reference signals of different magnitude.   
     
     
       8. The circuit breaker recited in claim 1 including, indicator means connected to said latch circuit means to receive a second latch signal whereby said indicator means is selectively activated.   
     
     
       9. The circuit breaker recited in claim 1 wherein, said switch means includes, movable contact means connected to said current path, and   coil means connected to said latch circuit means to receive said first latch signal to selectively move said movable contact means to interrupt said current path.     
     
     
       10. The circuit breaker recited in claim 9 including, coil drive means connected between said latch circuit means and said coil means.   
     
     
       11. The circuit breaker recited in claim 8 wherein, said latch circuit means includes first and second bistable circuits for producing said first and second latch signals.   
     
     
       12. The circuit breaker recited in claim 1 wherein, said counter means includes a plurality of counting circuits, and   said logic circuit means comprises an OR-gate.   
     
     
       13. The circuit breaker recited in claim 8 including, trip circuit means connected between said indicator means and said latch circuit means to activate said indicator means in response to said second latch signal.   
     
     
       14. The circuit breaker recited in claim 8 including, position sensor means connected to said indicator means to sense if the indicator means is activated.   
     
     
       15. The circuit breaker recited in claim 1 including, said latch circuit means includes first and second bistable circuits for producing said first and second latch signals, and   coil means connected to said latch circuit means to receive said first and second latch signals to selectively move said movable contact means to first and second latched positions respectively.   
     
     
       16. The circuit breaker recited in claim 1 including, said comparator means includes a plurality of comparator circuits each of which compares said sensor signal with a reference signal of different magnitude and produces a separate error signal representative of a difference between the sensor signal and the respective reference signal, and   said counter means includes a plurality of counting circuits, connected to a respective comparator circuit thereby producing counter signals representative of an error signal and a time duration thereof.   
     
     
       17. The circuit breaker recited in claim 8 wherein, said indicator means is located at a distance from the remainder of the circuit breaker.   
     
     
       18. A circuit breaker with multi-level switching capabilities comprising, current sensing means for producing a voltage signal representative of a current value in a current path,   reference signal producing means for producing a plurality of reference signals,   a plurality of comparator means,   each of said comparator means connected for comparing one of said plurality of reference signals with said sensor signal,   each of said comparator means operative to produce a separate error signal when said sensor signal differs from the respective one of said plurality of reference signals,   frequency generator means for producing a frequency signal,   a plurality of counter means connected to said frequency generator means and to a respective one of said comparator means,   each of said counter means operative to receive and count said frequency signal only when said comparator produces said error signal,   each of said counter means operative to produce a counter signal when said counter means has counted a prescribed number of said frequency signals representative of a prescribed time duration,   latch circuit means connected to all of said counter means to receive all of said counter signals and produce a first latch signal in response to the counter signal which is first received, and   switch means connected to said latch circuit means to receive said first latch signal whereby said switch means is operated to interrupt said current path.   
     
     
       19. A circuit breaker comprising, current sensing means for producing a sensor signal representative of a current value in a current path,   comparator means for comparing said sensor signal with a reference signal and operative to produce a time integrated error signal representative of the amplitude differential between said sensor signal and said reference signal and the time duration of the differential,   switch means connected to comparator means to receive said error signal whereby said switch means is selectively operated to interrupt said current path in response to said error signal,   indicator means located at a distance from the remainder of the circuit breaker,   trip circuit means connected between said indicator means and said switch means to activate said indicator means when said switch means is operated to interrupt said current path, and   position sensor means connected to said indicator means to sense if the indicator means is activated.   
     
     
       20. The circuit breaker recited in claim 19 wherein, said switch means includes, movable contact means connected to said current path,   coil means operative to selectively move said movable contact means to interrupt said current path, and   coil drive means connected between said comparator means and said coil means.     
     
     
       21. The circuit breaker recited in claim 19 wherein, said comparator means includes a plurality of comparator circuits each of which compares said sensor signal with a plurality of reference signals of different magnitudes.   
     
     
       22. The circuit breaker recited in claim 21 including, voltage divider network for providing said plurality of reference signals.   
     
     
       23. A circuit breaker with multi-level switching capabilities comprising, current sensing means for producing a voltage signal representative of a current value in a current path,   reference signal producing means for producing a plurality of reference signals,   a plurality of comparator means,   each of said comparator means connected for comparing one of said plurality of reference signals with said sensor signal,   each of said comparator means operative to produce a separate error signal when said sensor signal differs from the respective one of said plurality of reference signals,   frequency generator means for producing a frequency signal,   a plurality of counter means each of which is connected to said frequency generator means and to a respective one of said comparator means,   each of said counter means operative to receive and count said frequency signal only when said comparator produces said error signal,   each of said counter means operative to produce a counter signal when said counter means has counted a prescribed number of said frequency signals representative of a prescribed time duration,   latch circuit means connected to all of said counter means to receive all of said counter signals and produce a first latch signal in response to the counter signal which is first received, and   switch means connected to said latch circuit means to receive said first latch signal whereby said switch means is operated to interrupt said current path.   
     
     
       24. The circuit breaker recited in claim 23 wherein, said latch circuit means includes first and second bistable circuits for producing said first and second latch signals.   
     
     
       25. The circuit breaker recited in claim 23 including, logic circuit means connected between said counter means and said latch circuit means.   
     
     
       26. The circuit breaker recited in claim 23 wherein, said logic circuit means comprises an OR-gate.   
     
     
       27. The circuit breaker recited in claim 24 including, movable contact means connected in said current path, and   coil means connected to said latch circuit means to receive said first and second latch signals to selectively move said movable contact means to first and second latched positions respectively.   
     
     
       28. A circuit breaker comprising, current sensing means for producing a sensor signal representative of a current value in a current path,   reference signal producing means for producing at least one reference signal,   comparator means for comparing said reference signal with said sensor signal,   said comparator means includes a plurality of comparator circuits each of which compares said sensor signal with reference signals of different magnitude,   said comparator means operative to produce an error signal when said sensor signal differs from said reference signal,   frequency generator means for producing a frequency signal,   counter means connected to said frequency generator means and to said comparator means,   said counter means operative to receive and count said frequency signal when said comparator produces said error signal,   said counter means operative to produce a counter signal when said counter means has counted a prescribed number of said frequency signals,   latch circuit means connected to said counter means to receive said counter signal and produce a first latch signal in response thereto, and   switch means connected to said latch circuit means to receive said first latch signal whereby said switch means is operated to interrupt said current path.